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Talking Trees Live: Mediterranean Oak Borer with Davey Arborist Jess Running

Mediterranean Oak Borer: A New Threat to California’s Oak Trees

Arborist Jess Running shares what we need to know about this emerging Oak Borer!

When Did Mediterranean Oak Borer Arrive in the US?  

We aren’t entirely sure exactly when the Mediterranean Oak Borer (MOB) arrived, but it was spotted a few years ago. (00:03:26)

The important thing to share is once MOB established itself here, it started to rapidly spread into:

  • North and south Calistoga
  • Sonoma County
  • Napa County

And there’s nothing stopping it from spreading at this point. But don’t worry, we haven’t seen any infestations on grapevines, so your wine is ‘safe.’ (00:06:10)

What Trees are Affected by the Mediterranean Oak Borer?

This threatening tree insect seems to be attracted to one of the oldest and largest growing Oak tree species, the native California Valley Oak. (00:03:54)

MOB has also been spotted on Black Oaks and Sycamores. (00:06:23)

It will attack both stressed and healthy trees. (00:7:52, see visual at 00:08:20)

Continue reading below for more information:

>> What Are Signs of Tree Infestation?

>> Are There Any Treatments?

>> What Can Homeowners Do if MOB is Spotted?

Contact your local Davey certified arborist if you are unsure if you have MOB or want a free tree inspection.

What Are Signs of Tree Infestation?

A telltale symptom is a white ‘sawdust’ on the main trunk of the tree. Unfortunately, at this stage, the tree is most likely dead. (See visual at 00:06:36)

Trees infested by MOB will also show wilting and broken branches and discoloration of foliage.

Jess shares how his crew was removing a few dead branches and saw the limbs looked suspicious. Upon inspection, the tree was infested by MOB. (00:09:00)

A good arborist should be able to identify a MOB infestation because it is something out of the norm.

What is a good arborist? Here’s an analogy for you!

Davey’s certified arborists don’t just come to give your trees a “haircut,” we come to give your trees a “physical” from top-down!

A good arborist will walk around your entire tree.


Are There Any Treatments for MOB?

Treatment options are way too soon to make any recommendations. (00:11:04)

There are treatments currently available, but Davey is still doing more research to better understand the tree pest.

As a best practice, homeowners can protect their trees proactively by:

  • Clearing all deadwood from the tree (part of the tree that’s dead)
  • Having proper irrigation
  • Applying tree fertilization

Most importantly, having your trees checked at least once a year can save you a lot of problems. Too often homeowners call an arborist when it’s too late.

It is better to have your trees inspected when they are healthy.

What Can Homeowners Do if MOB Is Spotted?

Report all MOB sightings to the California Department of Food and Agriculture (CDFA).

Don’t move any infested wood to other areas.

Upcoming Talking Trees Live Series

Tune in for the next Talking Trees Live event! Each series will explore various tree care topics from damaging tree insects and diseases to landscape best practices and seasonal tree care tips. 

Have all your questions and concerns ready! You can ask them all live during the streaming interview. 

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Don’t have Facebook? No worries, you can access all the past videos here.

>>> Check out the schedule here for upcoming Talking Trees Live topics!

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